 <!DOCTYPE html>
<html>
 <head>
  <meta charset="utf-8">
  <title>下拉框</title>
  <link rel="stylesheet" href="js/bootstrap-3.4.1-dist/css/bootstrap.min.css">
  <link rel="stylesheet" href="js/bootstrap-3.4.1-dist/css/bootstrap-theme.css" />
  <script type="text/javascript" src="js/jquery-3.6.0.min.js"></script>
  <script type="text/javascript" src="js/bootstrap-3.4.1-dist/js/bootstrap.min.js"></script>
 </head>
 <body>
  <div class="dropdown">
   <button type="button" class="btn btn-success" id="meun" data-toggle="dropdown" aira-haspopup="true" aria-exapanded="true">下拉菜单<span class="caret"></span></button>
   <ul class="dropdown-menu" aira-labelledby="Menu">
    <li>< a href=" ">demo1</ a></li>
    <li>< a href="work01.html">demo2</ a></li>
   <li>< a href="work02.html">demo3</ a></li>
   </ul>
  </div>
 </body>
</html>